Method for producing h-shaped steel and rolling apparatus

ABSTRACT

To efficiently and stably produce an H-shaped steel product with a flange width larger than a conventional flange width, and separately shape by the same roll H-shaped steels different in flange width in the H-shaped steel product with a large flange width. A rolling mill that performs a rough rolling step is engraved with a plurality of calibers configured to shape a material to be rolled, the number of the plurality of calibers being seven or more; the plurality of calibers include a plurality of wedging calibers as calibers at a previous stage provided with projections configured to create splits vertically with respect to a width direction of the material to be rolled, and a plurality of bending calibers as calibers at a subsequent stage configured to bend flange corresponding portions of the material to be rolled formed by the wedging calibers; the wedging calibers include calibers configured to create two kinds of splits different in length; the bending calibers include calibers having dimensions according to two kinds of flange corresponding portions different in length formed in the material to be rolled in the wedging calibers; and in the bending calibers, reduction is performed in a state where end surfaces of the material to be rolled are in contact with peripheral surfaces of the calibers in shaping in at least one pass or more.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is based upon and claims the benefit of priority of the prior Japanese Patent Application No. 2016-002066, filed in Japan on Jan. 7, 2016, the entire contents of which are incorporated herein by reference.

TECHNICAL FIELD

The present invention relates to a method for producing H-shaped steel using a slab or the like having, for example, a rectangular cross section as a material, and a rolling apparatus.

BACKGROUND ART

In the case of producing H-shaped steel, a material such as a slab or a bloom extracted from a heating furnace is shaped into a raw blank (a material to be rolled in a so-called dog-bone shape) by a rough rolling mill (BD). Thicknesses of a web and flanges of the raw blank are subjected to reduction by an intermediate universal rolling mill, and flanges of a material to be rolled are subjected to width reduction and forging and shaping of end surfaces by an edger rolling mill close to the intermediate universal rolling mill. Then, an H-shaped steel product is shaped by a finishing universal rolling mill.

In such a method for producing H-shaped steel, there is a known technique in which in shaping a raw blank in a so-called dog-bone shape from a slab material having a rectangular cross section, splits are created on slab end surfaces in a first caliber at a rough rolling step, the splits are then widened or made deeper and edging rolling is performed in second and subsequent calibers, and the splits on the slab end surfaces are erased in subsequent calibers (refer to, for example, Patent Document 1).

Besides, for example, Patent Document 2 discloses a technique of forming flange-corresponding portions of H-shaped steel by creating splits on slab end surfaces, sequentially making the splits deeper, and then expanding the splits in a box caliber.

PRIOR ART DOCUMENT Patent Document

-   [Patent Document 1] Japanese Laid-open Patent Publication No.     H7-88501 -   [Patent Document 2] Japanese Laid-open Patent Publication No.     S60-21101

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention

In recent years, with an increase in size of structures and the like, production of large-size H-shaped steel products is desired. In particular, a product having flanges, which greatly contribute to strength and rigidity of H-shaped steel, wider than conventional flanges is desired. To produce the H-shaped steel product with widened flanges, it is necessary to shape a material to be rolled with a flange width larger than a conventional flange width from the shaping at the rough rolling step.

However, there is a limit in widening of flanges in the method in which splits are created on end surfaces of a material such as a slab (slab end surfaces) and the end surfaces are subjected to edging, and the spread is utilized for rough rolling, in the technique disclosed, for example, in Patent Document 1. In other words, in order to widen flanges in conventional rough rolling methods, techniques such as wedge designing (designing of a split angle), reduction adjustment, and lubrication adjustment are used to improve the spread. However, it is known that since none of the methods greatly contributes to a flange width, the rate of spread, which represents the rate of a spread amount of the flange width to an edging amount, is approximately 0.8 even under a condition that the efficiency at the initial stage of edging is the highest, decreases as the spread amount of the flange width increases under a condition that edging is repeated in the same caliber, and finally becomes approximately 0.5. It is also conceivable to increase the size of the material such as a slab itself to increase the edging amount, but there are circumstances where product flanges are not sufficiently widened because there are device limits in facility scale and reduction amount of a rough rolling mill.

Besides, for example, in the technique disclosed in Patent Document 2, flange-corresponding portions are shaped by edging rolling by a box caliber with a bottom surface in a flat shape, immediately on a material such as a slab provided with splits through no transition of split shapes or the like. Such a method tends to cause shape defects accompanying a rapid change in shape of a material to be rolled. In particular, the change in shape of the material to be rolled in such shaping is decided depending on the relation between the force of a contact portion between the material to be rolled and a roll, and, the flexural rigidity of the material to be rolled, and brings about a problem of being more likely to cause shape defects in the case of producing H-shaped steel with a flange width larger than a conventional flange width.

Further, recently, various sizes (dimensions) are desired also for a product increased in width of the flange as compared with the conventional one, and a technique of separately shaping by the same roll H-shaped steels different in flange width from slab materials having the same thickness is desired.

In view of such circumstances, an object of the present invention is to provide a method for producing H-shaped steel, capable of suppressing occurrence of shape defects in a material to be rolled by, in a rough rolling step using calibers in producing H-shaped steel, creating deep splits on end surfaces of a material such as a slab using projections in acute-angle tip shapes, and sequentially bending flange portions formed by the splits, to efficiently and stably produce an H-shaped steel product with a flange width larger than a conventional flange width, and capable of separately shaping by the same roll H-shaped steels different in flange width in the H-shaped steel product with a large flange width, and to provide a rolling apparatus.

Means for Solving the Problems

To achieve the above object, according to the present invention, there is provided a method for producing H-shaped steel, the method including: a rough rolling step; an intermediate rolling step; and a finish rolling step, wherein: a rolling mill that performs the rough rolling step is engraved with a plurality of calibers configured to shape a material to be rolled, the number of the plurality of calibers being seven or more; shaping in one or a plurality of passes is performed on the material to be rolled in the plurality of calibers; the plurality of calibers include a plurality of wedging calibers as calibers at a previous stage provided with projections configured to create splits vertically with respect to a width direction of the material to be rolled, and a plurality of bending calibers as calibers at a subsequent stage configured to bend flange corresponding portions of the material to be rolled formed by the wedging calibers; the wedging calibers include calibers configured to create two kinds of splits different in length; the bending calibers include calibers having dimensions according to two kinds of flange corresponding portions different in length formed in the material to be rolled in the wedging calibers; and in the bending calibers, reduction is performed in a state where end surfaces of the material to be rolled are in contact with peripheral surfaces of the calibers in shaping in at least one pass or more.

Each of the plurality of bending calibers may be provided with projections configured to bend the flange corresponding portions by pressing the projections against the flange corresponding portions formed by the wedging calibers.

All of the projections provided in the plurality of wedging calibers may have a tip angle of 25° or more and 40° or less.

The plurality of bending calibers may be provided at two stages in a configuration in which the calibers having dimensions according to the two kinds of flange corresponding portions different in length are provided with two kinds of projections different in tip angle, respectively; the projections of one of the bending calibers provided at the two stages may have a tip angle of 70° or more and 110° or less; and the projections of another of the bending calibers may have a tip angle of 130° or more and 170° or less.

The rough rolling step may be performed in a sizing mill and a rough rolling mill; the calibers at the previous stage of the plurality of wedging calibers and the plurality of bending calibers may be engraved on a roll of the sizing mill; and the calibers at the subsequent stage of the plurality of bending calibers may be engraved on a roll of the rough rolling mill.

The rough rolling step may be performed by one rough rolling mill; shaping by the calibers at the previous stage of the plurality of wedging calibers and the plurality of bending calibers may be performed in first heat by the rough rolling mill; and shaping by the calibers at the subsequent stage of the plurality of bending calibers may be performed in second heat by the rough rolling mill.

Materials same in thickness and different in width may be used to produce H-shaped steels same in web height and different in flange width.

According to the present invention from another viewpoint, there is provided a rolling apparatus performing a rough rolling step in production of H-shaped steel, wherein: the rolling apparatus is engraved with a plurality of calibers configured to perform shaping in one or a plurality of passes on a material to be rolled, the number of the plurality of calibers being seven or more; the plurality of calibers include a plurality of wedging calibers as calibers at a previous stage provided with projections configured to create splits vertically with respect to a width direction of the material to be rolled, and a plurality of bending calibers as calibers at a subsequent stage configured to bend flange corresponding portions of the material to be rolled formed by the wedging calibers; the wedging calibers include calibers configured to create two kinds of splits different in length; the bending calibers include calibers having dimensions according to two kinds of flange corresponding portions different in length formed in the material to be rolled in the wedging calibers; and the bending calibers have a configuration in which end surfaces of the material to be rolled are brought into contact with peripheral surfaces of the calibers in shaping in at least one pass or more.

Each of the plurality of bending calibers may be provided with projections configured to bend the flange corresponding portions by pressing the projections against the flange corresponding portions formed by the wedging calibers.

All of the projections provided in the plurality of wedging calibers may have a tip angle of 25° or more and 40° or less.

The plurality of bending calibers may be provided at two stages in a configuration in which the calibers having dimensions according to the two kinds of flange corresponding portions different in length are provided with two kinds of projections different in tip angle, respectively; the projections of one of the bending calibers provided at the two stages may have a tip angle of 70° or more and 110° or less; and the projections of another of the bending calibers may have a tip angle of 130° or more and 170° or less.

The rolling apparatus may include a sizing mill and a rough rolling mill; the calibers at the previous stage of the plurality of wedging calibers and the plurality of bending calibers may be engraved on a roll of the sizing mill; and the calibers at the subsequent stage of the plurality of bending calibers may be engraved on a roll of the rough rolling mill.

Effect of the Invention

According to the present invention, it becomes possible to suppress occurrence of shape defects in a material to be rolled by, in a rough rolling step using calibers in producing H-shaped steel, creating deep splits on end surfaces of a material such as a slab using projections in acute-angle tip shapes, and sequentially bending flange portions formed by the splits, to efficiently and stably produce an H-shaped steel product with a flange width larger than a conventional flange width, and to separately shape by the same roll H-shaped steels different in flange width in the H-shaped steel product with a large flange width.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic explanatory view about a production line for H-shaped steel.

FIG. 2 is a schematic explanatory view of a first caliber.

FIG. 3 is a schematic explanatory view of a second-first caliber.

FIG. 4 is a schematic explanatory view of a second-second caliber.

FIG. 5 is a schematic explanatory view of a third-first caliber.

FIG. 6 is a schematic explanatory view of a third-second caliber.

FIG. 7 is a schematic explanatory view of a fourth-first caliber.

FIG. 8 is a schematic explanatory view of a fourth-second caliber.

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, an embodiment of the present invention will be explained. Note that in this description and the drawings, components having substantially the same functional configurations are denoted by the same numerals to omit duplicated explanation.

FIG. 1 is an explanatory view about a production line T for H-shaped steel including a rolling facility 1 according to this embodiment. As illustrated in FIG. 1, in the production line T, a heating furnace 2, a sizing mill 3, a rough rolling mill 4, an intermediate universal rolling mill 5, and a finishing universal rolling mill 8 are arranged in order from the upstream side. Further, an edger rolling mill 9 is provided close to the intermediate universal rolling mill 5. Note that a steel material in the production line T for explanation is sometimes collectively described as a “material to be rolled A” and its shape is sometimes illustrated using broken lines, oblique lines and the like in the drawings.

As illustrated in FIG. 1, in the production line T, the material to be rolled A such as a slab 11 extracted from the heating furnace 2 is subjected to rough rolling in the sizing mill 3 and the rough rolling mill 4. Then, the material to be rolled A is subjected to intermediate rolling in the intermediate universal rolling mill 5. During the intermediate rolling, reduction is performed on end portions or the like (flange corresponding portions 12) of the material to be rolled by the edger rolling mill 9 as necessary. In a normal case, about four to six calibers in total are engraved on rolls of the sizing mill 3 and the rough rolling mill 4, and an H-shaped steel raw raw blank 13 is shaped by reverse rolling in a plurality of passes through those calibers, and the H-shaped steel raw blank 13 is subjected to application of reduction in a plurality of passes using a rolling mill train composed of two rolling mills such as the intermediate universal rolling mill 5 and the edger rolling mill 9, whereby an intermediate material 14 is shaped. The intermediate material 14 is subjected to finish rolling into a product shape in the finishing universal rolling mill 8, whereby an H-shaped steel product 16 is produced.

Next, caliber configurations and caliber shapes engraved on the sizing mill 3 and the rough rolling mill 4 illustrated in FIG. 1 will be explained below referring to the drawings. Note that generally on the rough rolling mill 4, in addition to a first caliber to a fourth caliber explained below, a caliber, which makes the material to be rolled A shaped by those calibers, into a so-called dog-bone shaped H-shaped steel raw blank 13 is further provided, but this caliber is conventionally known one and therefore its illustration and explanation will be omitted in this description. Besides, the heating furnace 2, the intermediate universal rolling mill 5, the finishing universal rolling mill 8, the edger rolling mill 9 and the like in the production line T are standard apparatuses conventionally used in production of the H-shaped steel, and their apparatus configurations and so on are already known and therefore their explanation will be omitted in this description.

FIG. 2 to FIG. 8 are schematic explanatory views about calibers engraved on the sizing mill 3 and the rough rolling mill 4 which perform a rough rolling step. All of the first caliber to the fourth caliber explained here may be engraved, for example, on the sizing mill 3, or the first caliber to the fourth caliber may be engraved separately on the sizing mill 3 and the rough rolling mill 4. In other words, the first caliber to the fourth caliber may be engraved across both the sizing mill 3 and the rough rolling mill 4, or may be engraved on one of the rolling mills. In the rough rolling step in production of standard H-shaped steel, shaping in one or a plurality of passes is performed in each of the calibers.

In this embodiment, each of the second caliber, the third caliber, and the fourth caliber is composed of two kinds of calibers different in dimension and shape, the second caliber is composed of a second-first caliber and a second-second caliber, the third caliber is composed of a third-first caliber and a third-second caliber, and the fourth caliber is composed of a fourth-first caliber and a fourth-second caliber. Note that in FIG. 2 to FIG. 5, a schematic final pass shape of the material to be rolled A in shaping in each caliber is illustrated by broken lines.

FIG. 2 is a schematic explanatory view of a first caliber K1. The first caliber K1 is engraved on an upper caliber roll 20 and a lower caliber roll 21 which are a pair of horizontal rolls, and the material to be rolled A is subjected to reduction and shaping in a roll gap between the upper caliber roll 20 and the lower caliber roll 21. Further, a peripheral surface of the upper caliber roll 20 (namely, an upper surface of the first caliber K1) is formed with a projection 25 protruding toward the inside of the caliber. Further, a peripheral surface of the lower caliber roll 21 (namely, a bottom surface of the first caliber K1) is formed with a projection 26 protruding toward the inside of the caliber. These projections 25, 26 have tapered shapes, and dimensions such as a protrusion length of the projection 25 and the projection 26 are configured to be equal to each other. A height (protrusion length) of the projections 25, 26 is h1 and a tip portion angle thereof is θ1 a.

In the first caliber K1, the projections 25, 26 are pressed against upper and lower end portions (slab end surfaces) of the material to be rolled A and thereby form splits 28, 29. Here, a tip portion angle (also called a wedge angle) θ1 a of the projections 25, 26 is desirably, for example, 25° or more and 40° or less.

The lower limit of the wedge angle is normally decided by the strength of the roll. The material to be rolled A is brought into contact with the rolls (the upper caliber roll 20 and the lower caliber roll 21 in the first caliber K1), and the rolls expand due to heat receiving during the contact and contract due to cooling of the rolls when the material to be rolled A is separated from the rolls. During shaping, these cycles are repeated, in which if the wedge angle is too small, the heat inputted from the material to be rolled A becomes more likely to be inputted from right and left of the projections because of the small thicknesses of the projections (the projections 25, 26 in the first caliber K1), and the rolls are more likely to become higher in temperature. If the rolls become high in temperature, a thermal amplitude increases to cause a heat crack, possibly leading to a roll breakage.

On the other hand, when the wedge angle becomes large, deformation due to spread occurs in forming the splits in each caliber (the splits 28, 29 in the first caliber K1) occurs to decrease the generation efficiency of flange particularly in shaping a second caliber K2 or subsequent thereto explained below.

As a result of earnest analysis and evaluation by the present inventors from the above viewpoint, it is desirable that the range of the wedge angle θ1 a is 25° or more and 40° or less in the caliber configuration according to this embodiment.

Here, a caliber width of the first caliber K1 is preferably substantially equal to the thickness of the material to be rolled A (namely, a slab thickness). Specifically, when the widths of the caliber at the tip portion portions of the projections 25, 26 formed in the first caliber K1 is set to be the same as the slab thickness, a right-left centering property of the material to be rolled A is suitably secured. Further, it is preferable that such a configuration of the caliber dimension brings the projections 25, 26 and part of caliber side surfaces (side walls) into contact with the material to be rolled A at upper and lower end portions (slab end surfaces) of the material to be rolled A during shaping in the first caliber K1 as illustrated in FIG. 2 so as to prevent active reduction at the upper surface and the bottom surface of the first caliber K1 from being performed on the slab upper and lower end portions divided into four elements (parts) by the splits 28, 29. This is because the reduction by the upper surface and the bottom surface of the caliber causes elongation of the material to be rolled A in the longitudinal direction to decrease the generation efficiency of the flanges (later-described flange portions 100). In other words, in the first caliber K1, a reduction amount at the projections 25, 26 (reduction amount ΔT at wedge tips) at the time when the projections 25, 26 are pressed against the upper and lower end portions (slab end surfaces) of the material to be rolled A to form the splits 28, 29 is made sufficiently larger than a reduction amount at the slab upper and lower end portions (reduction amount ΔE at slab end surfaces) and thereby forms the splits 28, 29.

FIG. 3 is a schematic explanatory view of a second caliber K2-1. The second caliber K2-1 is engraved on an upper caliber roll 30 and a lower caliber roll 31 which are a pair of horizontal rolls. A peripheral surface of the upper caliber roll 30 (namely, an upper surface of the second caliber K2-1) is formed with a projection 35 protruding toward the inside of the caliber. Further, a peripheral surface of the lower caliber roll 31 (namely, a bottom surface of the second caliber K2-1) is formed with a projection 36 protruding toward the inside of the caliber. These projections 35, 36 have tapered shapes, and dimensions such as a protrusion length of the projection 35 and the projection 36 are configured to be equal to each other. A tip portion angle of the projections 35, 36 is desirably a wedge angle θ1 b of 25° or more and 40° or less.

A height (protrusion length) h2 of the projections 35, 36 is configured to be larger than the height h1 of the projections 25, 26 of the first caliber K1 so as to be h2>h1. Here, as explained above, the tip portion angle (wedge angle θ1 b) of the projections 35, 36 is preferably the same as the tip portion angle of the projections 25, 26 in the first caliber K1 (namely, θ1 a=θ1 b).

Here, the height h2 of the projections 35, 36 formed in the second caliber K2-1 is larger than the height h1 of the projections 25, 26 formed in the first caliber K1, and an intrusion length into the upper and lower end portions (slab end surfaces) of the material to be rolled A is also similarly larger in the second caliber K2-1. An intrusion depth into the material to be rolled A of the projections 35, 36 in the second caliber K2-1 is the same as the height h2 of the projections 35, 36. In other words, an intrusion depth h1′ into the material to be rolled A of the projections 25, 26 in the first caliber K1 and the intrusion depth h2 into the material to be rolled A of the projections 35, 36 in the second caliber K2-1 satisfy a relation of h1′<h2.

Further, angles θf formed between caliber upper surfaces 30 a, 30 b and caliber bottom surfaces 31 a, 31 b facing the upper and lower end portions (slab end surfaces) of the material to be rolled A, and, inclined surfaces of the projections 35, 36, are configured to be about 90° (almost right angle) at all of four locations illustrated in FIG. 3.

Since the intrusion length of the projections at the time when pressed against the upper and lower end portions (slab end surfaces) of the material to be rolled A is large as illustrated in FIG. 3, shaping is performed to make the splits 28, 29 formed in the first caliber K1 deeper in the second caliber K2-1 to thereby form the splits 38, 39.

Further, the shaping in the second caliber K2-1 is performed by multi-pass, and in the multi-pass shaping, shaping is performed to bring the upper and lower end portions (slab end surfaces) of the material to be rolled A into contact with the caliber upper surfaces 30 a, 30 b and the caliber bottom surfaces 31 a, 31 b facing them in the final pass. This is because if the upper and lower end portions of the material to be rolled A are made to be out of contact with the inside of the caliber in all passes in the second caliber K2-1, a shape defect such as flange corresponding portions (the later-described flange portions 100) being shaped to be laterally asymmetrical possibly occurs, bringing about a problem in terms of a material passing property.

FIG. 4 is a schematic explanatory view of a second caliber K2-2. The second caliber K2-2 is engraved on an upper caliber roll 40 and a lower caliber roll 41 which are a pair of horizontal rolls. A peripheral surface of the upper caliber roll 40 (namely, an upper surface of the second caliber K2-2) is formed with a projection 45 protruding toward the inside of the caliber. Further, a peripheral surface of the lower caliber roll 41 (namely, a bottom surface of the second caliber K2-2) is formed with a projection 46 protruding toward the inside of the caliber. These projections 45, 46 have tapered shapes, and dimensions such as a protrusion length of the projection 45 and the projection 46 of the second caliber K2-2 are configured to be equal to each other.

The shapes of the projections 45, 46 are similar shapes as the shapes of the projections 35, 36 of the aforementioned second caliber K2-1, in which a tip portion angle is similarly a wedge angle θ1 b of 25° or more and 40° or less. Further, a height h2′ of the projections 45, 46 is configured to be larger than the height h2 of the aforementioned projections 35, 36 (namely, h2<h2′).

Further, angles θf formed between caliber upper surfaces 40 a, 40 b and caliber bottom surfaces 41 a, 41 b facing the upper and lower end portions (slab end surfaces) of the material to be rolled A, and, inclined surfaces of the projections 45, 46, are configured to be about 90° (almost right angle) at all of four locations illustrated in FIG. 4.

Since an intrusion length of the projections 45, 46 at the time when pressed against the upper and lower end portions (slab end surfaces) of the material to be rolled A is configured to be larger than that in any of the first caliber K1 and the second caliber K2-1 as illustrated in FIG. 4, further deeper splits 48, 49 are formed in the second caliber K2-2.

Further, the shaping in the second caliber K2-2 is performed by multi-pass, and in the multi-pass shaping, shaping is performed to bring the upper and lower end portions (slab end surfaces) of the material to be rolled A into contact with the caliber upper surfaces 40 a, 40 b and the caliber bottom surfaces 41 a, 41 b facing them in the final pass. This is because if the upper and lower end portions of the material to be rolled A are made to be out of contact with the inside of the caliber in all passes in the second caliber K2-2, a shape defect such as flange corresponding portions (the later-described flange portions 100) being shaped to be laterally asymmetrical possibly occurs, bringing about a problem in terms of a material passing property.

The second calibers K2-1, K2-2 can be used properly as needed, and there are conceivable cases such as a case of performing shaping by passing the material to be rolled A passed through the first caliber K1 through only the second caliber K2-1 and a case of performing shaping by passing the material to be rolled A passed through the first caliber K1 through both the second caliber K2-1 and the second caliber K2-2. Note that FIG. 3 illustrates the shape of a material to be rolled in the case of shaping an H-shaped steel raw blank small in flange half-width of the flange corresponding portions (the parts corresponding to the later-described flange portions 100) by passing the material through only the second caliber K2-1, and FIG. 4 illustrates the shape of a material to be rolled in the case of using a material having a larger slab width than (different in material section from) that in the case illustrated in FIG. 3 and shaping an H-shaped steel raw blank large in flange half-width of the flange corresponding portions (the parts corresponding to the later-described flange portions 100) by passing the material through both the second caliber K2-1 and the second caliber K2-2. Such proper use enables shaping to be performed separately in the case where the flange half-width of the flange corresponding portions (the parts corresponding to the later-described flange portions 100) shaped by forming splits in the upper and lower end portions (slab end surfaces) of the material to be rolled A is small and the case where the flange half-width is large. In other words, use of the two calibers (second calibers K2-1, K2-2) enables shaping for producing two kinds of products different in flange width, as the H-shaped steel being the final product, from materials which are the same in slab thickness and different in width.

As explained above, at the time of performing shaping separately in the case where the flange half-width of the flange corresponding portions (the parts corresponding to the later-described flange portions 100) is small and the case where the flange half-width is large, the slabs used as the materials are materials which are the same in thickness and different in width (slab width). Accordingly, use of the material small in slab width in the case of performing shaping by passing the material through only the second caliber K2-1 and use of the material large in slab width in the case of performing shaping by passing the material through both the second caliber K2-1 and the second caliber K2-2, enables shaping separately in the case where the flange half-width is small (see FIG. 3) and the case where the flange half-width is large (see FIG. 4).

Note that the first caliber K1 and the second calibers K2-1, K2-2 explained above are for forming splits in the upper and lower end portions (slab end surfaces) of the material to be rolled A, and are therefore called wedging calibers.

FIG. 5 is a schematic explanatory view of a third caliber K3-1. The third caliber K3-1 is engraved on an upper caliber roll 50 and a lower caliber roll 51 which are a pair of horizontal rolls. A peripheral surface of the upper caliber roll 50 (namely, an upper surface of the third caliber K3-1) is formed with a projection 55 protruding toward the inside of the caliber. Further, a peripheral surface of the lower caliber roll 51 (namely, a bottom surface of the third caliber K3-1) is formed with a projection 56 protruding toward the inside of the caliber. These projections 55, 56 have tapered shapes, and dimensions such as a protrusion length of the projection 55 and the projection 56 are configured to be equal to each other.

A tip portion angle θ2 of the projections 55, 56 is configured to be larger than the aforementioned angle θ1 b, and an intrusion depth h3 of the projections 55, 56 into the material to be rolled A is smaller than the intrusion depth h2 of the projections 35, 36 in the second caliber K2-1 (namely, h3<h2).

Further, angles θf framed between caliber upper surfaces 50 a, 50 b and caliber bottom surfaces 51 a, 51 b facing the upper and lower end portions (slab end surfaces) of the material to be rolled A, and, inclined surfaces of the projections 55, 56, are configured to be about 90° (almost right angle) at all of four locations illustrated in FIG. 5.

As illustrated in FIG. 5, in the third caliber K3-1, the splits 38, 39 formed in the second caliber K2-1 at the upper and lower end portions (slab end surfaces) of the material to be rolled A passed through the second caliber K2-1 are pressed against the projections 55, 56 and thereby become splits 58, 59. Specifically, in a final pass in shaping in the third caliber K3-1, a deepest portion angle (hereinafter, also called a split angle) of the splits 58, 59 becomes θ2. In other words, shaping is performed so that divided parts (the parts corresponding to the later-described flange portions 100) shaped along with the formation of the splits 38, 39 in the second caliber K2-1 are bent outward.

Besides, the shaping in the third caliber K3-1 is performed by at least one pass or more, and in the shaping, shaping is performed to bring the upper and lower end portions (slab end surfaces) of the material to be rolled A into contact with the caliber upper surfaces 50 a, 50 b and the caliber bottom surfaces 51 a, 51 b facing them in the final pass. This is because if the upper and lower end portions of the material to be rolled A are made to be out of contact with the inside of the caliber in all passes in the third caliber K3-1, a shape defect such as flange corresponding portions (the later-described flange portions 100) being shaped to be laterally asymmetrical possibly occurs, bringing about a problem in terms of a material passing property.

FIG. 6 is a schematic explanatory view of a third caliber K3-2. The third caliber K3-2 is engraved on an upper caliber roll 60 and a lower caliber roll 61 which are a pair of horizontal rolls. A peripheral surface of the upper caliber roll 60 (namely, an upper surface of the third caliber K3-2) is formed with a projection 65 protruding toward the inside of the caliber. Further, a peripheral surface of the lower caliber roll 61 (namely, a bottom surface of the third caliber K3-2) is formed with a projection 66 protruding toward the inside of the caliber. These projections 65, 66 have tapered shapes, and dimensions such as a protrusion length of the projection 65 and the projection 66 are configured to be equal to each other.

The shapes of the projections 65, 66 are similar shapes as the shapes of the projections 55, 56 of the aforementioned third caliber K3-1, in which a tip portion angle is similarly a wedge angle θ2 and a height h3′ of the projections 65, 66 is configured to be larger than the height h3 of the projections 55, 56 (namely, h3<h3′). Further, angles θf formed between caliber upper surfaces 60 a, 60 b and caliber bottom surfaces 61 a, 61 b facing the upper and lower end portions (slab end surfaces) of the material to be rolled A, and, inclined surfaces of the projections 65, 66, are configured to be about 90° (almost right angle) at all of four locations illustrated in FIG. 6.

As illustrated in FIG. 6, in the third caliber K3-2, the splits 48, 49 formed in the second caliber K2-2 at the upper and lower end portions (slab end surfaces) of the material to be rolled A passed through the second caliber K2-2 are pressed against the projections 65, 66 and thereby become splits 68, 69. Specifically, in a final pass in shaping in the third caliber K3-2, a deepest portion angle (hereinafter, also called a split angle) of the splits 68, 69 becomes θ2. In other words, shaping is performed so that divided parts (the parts corresponding to the later-described flange portions 100) shaped along with the formation of the splits 48, 49 in the second caliber K2-2 are bent outward.

Besides, the shaping in the third caliber K3-2 is performed by at least one pass or more, and in the shaping, shaping is performed to bring the upper and lower end portions (slab end surfaces) of the material to be rolled A into contact with the caliber upper surfaces 60 a, 60 b and the caliber bottom surfaces 61 a, 61 b facing them in the final pass. This is because if the upper and lower end portions of the material to be rolled A are made to be out of contact with the inside of the caliber in all passes in the third caliber K3-2, a shape defect such as flange corresponding portions (the later-described flange portions 100) being shaped to be laterally asymmetrical possibly occurs, bringing about a problem in terms of a material passing property.

Though both the third caliber K3-1 and the third caliber K3-2 explained referring to FIG. 5 and FIG. 6 are for calibers for bending outward the divided parts (the parts corresponding to the later-described flange portions 100) shaped by the splits, the third caliber K3-1 is for shaping the material to be rolled A shaped by using only the second caliber K2-1 as a caliber at a previous stage, whereas the third caliber K3-2 is for shaping the material to be rolled A shaped by using the second caliber K2-1 and the second caliber K2-2 as calibers at a previous stage.

More specifically, in the case of producing two kinds of products different in flange width at the same roll chance, the third caliber K3-1 is used when producing a product small in flange width and the third caliber K3-2 is used when producing a product large in flange width. Naturally, as is found by comparing FIG. 5 and FIG. 6, shaping is performed so that the flange corresponding portions (the later-described flange portions 100) shaped by the third caliber K3-2 are larger in flange half-width than the flange corresponding portions (the later-described flange portions 100) shaped by the third caliber K3-1.

Note that the split angle θ2 of the third calibers K3-1, K3-2 is desirably set, for example, to 70° or more and 110° or less. In the case where the split angle θ2 is less than 70° or more than 110°, shape defects such as deformation unbalance between right and left flange portions 80 and crush of the outside surfaces of the flange portions 80 possibly occur, and a shape defect that a middle portion of the outside surface of the flange portion 80 is formed into a material-accumulated shape in shaping the dog-bone shape in a known flat shaping caliber to cause a product flaw possibly occurs.

As a result of earnest analysis and evaluation by the present inventors from the above viewpoint, it is desirable that the range of the split angle θ2 is 70° or more and 110° or less in the caliber configuration according to this embodiment.

FIG. 7 is a schematic explanatory view of a fourth caliber K4-1. The fourth caliber K4-1 is engraved on an upper caliber roll 70 and a lower caliber roll 71 which are a pair of horizontal rolls. A peripheral surface of the upper caliber roll 70 (namely, an upper surface of the fourth caliber K4-1) is formed with a projection 75 protruding toward the inside of the caliber. Further, a peripheral surface of the lower caliber roll 71 (namely, a bottom surface of the fourth caliber K4-1) is formed with a projection 76 protruding toward the inside of the caliber. These projections 75, 76 have tapered shapes, and dimensions such as a protrusion length of the projection 75 and the projection 76 are configured to be equal to each other.

A tip portion angle θ3 of the projections 75, 76 is configured to be larger than the aforementioned angle θ2, and an intrusion depth h4 of the projections 75, 76 into the material to be rolled A is smaller than the intrusion depth h3 of the projections 55, 56 (namely, h4<h3).

Further, angles θf formed between caliber upper surfaces 70 a, 70 b and caliber bottom surfaces 71 a, 71 b facing the upper and lower end portions (slab end surfaces) of the material to be rolled A, and, inclined surfaces of the projections 75, 76, are configured to be about 90° (almost right angle) at all of four locations illustrated in FIG. 7.

As illustrated in FIG. 7, in the fourth caliber K4-1, the splits 58, 59 formed in the third caliber K3-1 at the upper and lower end portions (slab end surfaces) of the material to be rolled A passed through the third caliber K3-1 are pressed against the projections 75, 76 and thereby become splits 78, 79. Specifically, in a final pass in shaping in the fourth caliber K4-1, a deepest portion angle (hereinafter, also called a split angle) of the splits 78, 79 becomes θ3. In other words, shaping is performed so that divided parts (the parts corresponding to the later-described flange portions 100) shaped along with the formation of the splits 58, 59 in the third caliber K3-1 are bent outward.

Besides, the shaping in the fourth caliber K4-1 is performed by at least one pass or more, and in the shaping, shaping is performed to bring the upper and lower end portions (slab end surfaces) of the material to be rolled A into contact with the caliber upper surfaces 70 a, 70 b and the caliber bottom surfaces 71 a, 71 b facing them in the final pass. This is because if the upper and lower end portions of the material to be rolled A are made to be out of contact with the inside of the caliber in all passes in the fourth caliber K4-1, a shape defect such as flange corresponding portions (the later-described flange portions 100) being shaped to be laterally asymmetrical possibly occurs, bringing about a problem in terms of a material passing property.

FIG. 8 is a schematic explanatory view of a fourth caliber K4-2. The fourth caliber K4-2 is engraved on an upper caliber roll 80 and a lower caliber roll 81 which are a pair of horizontal rolls. A peripheral surface of the upper caliber roll 80 (namely, an upper surface of the fourth caliber K4-2) is formed with a projection 85 protruding toward the inside of the caliber. Further, a peripheral surface of the lower caliber roll 81 (namely, a bottom surface of the fourth caliber K4-2) is formed with a projection 86 protruding toward the inside of the caliber. These projections 85, 86 have tapered shapes, and dimensions such as a protrusion length of the projection 85 and the projection 86 are configured to be equal to each other.

The shapes of the projections 85, 86 are similar shapes as the shapes of the projections 75, 76 of the aforementioned fourth caliber K4-1, in which a tip portion angle is similarly a wedge angle θ3 and a height h3′ of the projections 85, 86 is configured to be larger than the height h4 of the projections 75, 76 (namely, h4<h4′). Further, angles θf formed between caliber upper surfaces 80 a, 80 b and caliber bottom surfaces 81 a, 81 b facing the upper and lower end portions (slab end surfaces) of the material to be rolled A, and, inclined surfaces of the projections 85, 86, are configured to be about 90° (almost right angle) at all of four locations illustrated in FIG. 8.

As illustrated in FIG. 8, in the fourth caliber K4-2, the splits 68, 69 formed in the third caliber K3-2 at the upper and lower end portions (slab end surfaces) of the material to be rolled A passed through the third caliber K3-2 are pressed against the projections 85, 86 and thereby become splits 88, 89. Specifically, in a final pass in shaping in the fourth caliber K4-2, a deepest portion angle (hereinafter, also called a split angle) of the splits 88, 89 becomes θ3. In other words, shaping is performed so that divided parts (the parts corresponding to the later-described flange portions 100) shaped along with the formation of the splits 68, 69 in the third caliber K3-2 are bent outward. The parts of the upper and lower end portions of the material to be rolled A shaped in this manner are parts corresponding to flanges of a later-described H-shaped steel product and called the flange portions 100 here.

Besides, the shaping in the fourth caliber K4-2 is performed by at least one pass or more, and in the shaping, shaping is performed to bring the upper and lower end portions (slab end surfaces) of the material to be rolled A into contact with the caliber upper surfaces 80 a, 80 b and the caliber bottom surfaces 81 a, 81 b facing them in the final pass. This is because if the upper and lower end portions of the material to be rolled A are made to be out of contact with the inside of the caliber in all passes in the fourth caliber K4-2, a shape defect such as the flange portions 100 being shaped to be laterally asymmetrical possibly occurs, bringing about a problem in terms of a material passing property.

Note that the split angle θ3 of the fourth calibers K4-1, K4-2 is desirably set to an angle slightly smaller than 180°, and is desirably set to, for example, 130° or more and 170° or less. This is because if the split angle θ3 is set to 180°, spread occurs on the outside of the flange portions 100 at the time of decreasing the web thickness in the flat shaping caliber being the next step, and an overfill is likely to occur in rolling in the flat shaping caliber. More specifically, since the spread amount on the outside of the flange portions 100 is decided according to the shape of the flat shaping caliber at the next step and to the reduction amount of the web thickness, it is desirable that the split angle θ3 here is suitably decided in consideration of the shape of the flat shaping caliber and the reduction amount of the web thickness.

Though both the fourth caliber K4-1 and the fourth caliber K4-2 explained referring to FIG. 7 and FIG. 8 are calibers for bending outward the divided parts (the later-described flange portions 100) shaped by the splits, the fourth caliber K4-1 is for shaping the material to be rolled A shaped by using the third caliber K3-1 as a caliber at a previous stage, whereas the fourth caliber K4-2 is for shaping the material to be rolled A shaped by using the third caliber K3-2 as a caliber at a previous stage.

More specifically, in the case of producing two kinds of products different in flange width at the same roll chance, the fourth caliber K4-1 is used when producing a product small in flange width and the fourth caliber K4-2 is used when producing a product large in flange width. Naturally, as is found by comparing FIG. 7 and FIG. 8, shaping is performed so that the flange portions 100 shaped by the fourth caliber K4-2 are larger in flange half-width than the flange portions 100 shaped by the fourth caliber K4-1.

Note that the third calibers K3-1, K3-2 and the fourth calibers K4-1 K4-2 explained above perform shaping of bending outward the divided parts (the later-described flange portions 100) formed at the upper and lower end portions (slab end surfaces) of the material to be rolled A, and are therefore called bending calibers.

On the material to be rolled A shaped by the first caliber K1 to the fourth calibers K4-1, K4-2 explained above, reduction and shaping is further performed using a known caliber (flat shaping caliber), thereby shaping an H-shaped steel raw blank 13 in a so-called dog-bone shape. Normally, the web thickness is then decreased by the flat shaping caliber for decreasing the thickness of a portion corresponding to the slab thickness. Thereafter, the rolling mill train composed of two rolling mills such as the intermediate universal rolling mill 5 and the edger rolling mill 9 illustrated in FIG. 1 is used to apply reduction in a plurality of passes to thereby shape an intermediate material 14. The intermediate material 14 is then subjected to finish rolling into a product shape in the finishing universal rolling mill 8, whereby an H-shaped steel product 16 is produced.

Steps in the case of producing two kinds of H-shaped steel products different in half-width of the flange portion 100 from slab materials having the same thickness and different widths in the rolling and shaping by the first caliber K1 to the fourth calibers K4-1, K4-2 of the H-shaped steel raw blank 13 will be briefly explained. Specifically, shaping of the H-shaped steel raw blank in the case of producing a first H-shaped steel product (small-width product) having a flange half-width of L1 and a second H-shaped steel product (large-width product) having a flange half-width of L2 (>L1) will be explained.

First of all, on the slab materials 11 extracted from the heating furnace 2, formation of the splits 28, 29 is performed on upper and lower end portions in the first caliber K1 (see FIG. 2). Subsequently, in the second caliber K2-1, shaping is performed to make the splits 28, 29 deeper to form the splits 38, 39. The steps in the first caliber K1 and the second caliber K2-1 are performed commonly on the first H-shaped steel product and the second H-shaped steel product (see FIG. 3). At this time, the thicknesses of the slab materials 11 to be used are the same for both of them, but the slab width of the material corresponding to the second H-shaped steel product is larger.

In production of the first H-shaped steel product, the material to be rolled A is shaped in the third caliber K3-1, the splits 38, 39 are spread out, and the divided parts (the parts corresponding to the later-described flange portions 100) shaped along with the formation of the splits 58, 59 are bent outward (see FIG. 5). Then, the material to be rolled A shaped in the third caliber K3-1 is further shaped in the fourth caliber K4-1, in which the divided parts (the parts corresponding to the later-described flange portions 100) shaped along with the formation of the splits 78, 79 are further bent outward (see FIG. 7).

Here, the flange half-width L1 of the first H-shaped steel product depends on the half-width of the flange corresponding portions shaped along with the formation of the splits 38, 39 in the second caliber K2-1.

On the other hand, in production of the second H-shaped steel product, shaping of the upper and lower end surfaces of the material to be rolled A shaped in the second caliber K2-1 is performed, and then the material to be rolled A is subjected to shaping of making the formed splits 38, 39 deeper in the second caliber K2-2 to form the splits 48, 49 (see FIG. 4). The material to be rolled A is then shaped in the second caliber K2-2 and then further shaped in the third caliber K3-2, whereby the splits 48, 49 are spread out, and the divided parts (the parts corresponding to the later-described flange portions 100) shaped along with the formation of the splits 68, 69 are bent outward (see FIG. 6). Subsequently, the material to be rolled A shaped in the third caliber K3-2 is further shaped in the fourth caliber K4-2, in which the divided parts (the parts corresponding to the later-described flange portions 100) shaped along with the formation of the splits 88, 89 are bent outward (see FIG. 8).

Here, the flange half-width L2 of the second H-shaped steel product depends on the half-width of the flange corresponding portions shaped along with the formation of the splits 48, 49 in the second caliber K2-2.

The two kinds of H-shaped steel raw blanks thus shaped have the flange half-widths L1 and L2 different from each other as explained above. On the other hand, in the widths of the H-shaped steel raw blanks, the widths of the parts corresponding to the webs are almost equal. Shaping the H-shaped steel raw blanks with the above configurations enables rolling and shaping of the two kinds of H-shaped steel raw blanks at the same roll chance in the rolling and shaping in the intermediate universal rolling mill 5, the edger rolling mill 9, and the finishing universal rolling mill 8 at a subsequent stage.

Table 1 is a table made by summarizing shaping processes of the H-shaped steel raw blanks in the case of producing the aforementioned first H-shaped steel product (small-width product) having a flange half-width of L1 and second H-shaped steel product (large-width product) having a flange half-width of L2 (>L1). Note that caliber names G1 to G4-2 in Table 1 correspond to the first caliber K1 to the fourth caliber K4-2, the stand No. is an example in the case of separating the rolling mill engraving the caliber into two mills, and description of 1st time and 2nd time indicates an example of rolling calibers and their order in the case where when only one rolling stand for performing rough rolling is provided, operation is performed in two separate roll chances for heating twice in order to compensate for insufficiency of a roll barrel length.

Further, the numbers of 1 to 4 regarding the first H-shaped steel product (small-width product) and the numbers of 1 to 5 regarding the second H-shaped steel product (large-width product) indicate calibers through which the material is passed and the order of the calibers.

TABLE 1 NAME FUNCTION SMALL WIDTH LARGE WIDTH STAND ROLLING G1 GROOVING {circle around (1)} {circle around (1)} No. 1 FIRST TIME G2-1 SHALLOW SPLIT, SHAPING AFTER {circle around (2)} {circle around (2)} No. 1 FIRST TIME CONTACT WITH TIP END G2-2 DEEP SPLIT, SHAPING AFTER ↓ {circle around (3)} No. 1 FIRST TIME CONTACT WITH TIP END G3-1 BENDING FOR SMALL {circle around (3)} ↓ No. 1 FIRST TIME WIDTH, SHAPING AFTER CONTACT WITH TIP END G3-2 BENDING FOR LARGE ↓ {circle around (4)} No. 1 FIRST TIME WIDTH, SHAPING AFTER CONTACT WITH TIP END G4-1 BENDING FOR SMALL {circle around (4)} ↓ No. 2 SECOND TIME WIDTH, SHAPING AFTER CONTACT WITH TIP END G4-2 BENDING FOR LARGE ↓ {circle around (5)} No. 2 SECOND TIME WIDTH, SHAPING AFTER CONTACT WITH TIP END

By the shaping processes as listed in Table 1, the first H-shaped steel product (small-width product) and the second H-shaped steel product (large-width product) are shaped separately. Note that as illustrated in Table 1 and the explanation of this embodiment, in the case of separately shaping the first H-shaped steel product (small-width product) and the second H-shaped steel product (large-width product), a second caliber 2-1 (G2-1 in Table) is used for both of the products. This is for stably forming splits without causing lateral nonuniformity of the flange corresponding portions and poor material passage when further deepening the splits 28, 29 formed at the upper and lower end portions of the material to be rolled A in the first caliber K1. In particular, in the case of producing, for example, an H-shaped steel product having a large flange width such as a flange width of 300 mm or more, stable shaping of the flange corresponding portions and formation of the splits are performed by using the second caliber 2-1 for correcting the shapes of the flange corresponding portions once before the flange corresponding portions are shaped to be laterally nonuniform.

The first caliber K1 to the fourth caliber K4-2 according to this embodiment are used to create splits in the upper and lower end portions (slab end surfaces) of the material to be rolled A and perform processing of bending to right and left the portions separated to right and left by the splits to perform the shaping of forming the flange portions 100 as explained above, thereby enabling shaping of the H-shaped steel raw blank 13 without performing vertical reduction on the upper and lower end surfaces of the material to be rolled A (slab). In short, it becomes possible to shape the H-shaped steel raw blank 13 with the flange width made wider as compared with the rough rolling method of reducing at all times the slab end surfaces conventionally performed, resulting in production of a final product (H-shaped steel) having a large flange width.

Furthermore, in the shaping method, for example, as listed in Table 1 using the first caliber K1 to the fourth caliber K4-2, the slab materials which are the same in thickness and different in width are used to shape two kinds of raw blanks such as one having a small half-width of the flange portion 100 shaped using the third caliber K3-1 and the fourth caliber K4-1 and one having a large half-width of the flange portion 100 shaped using the third caliber K3-2 and the fourth caliber K4-2, and they are shaped in a so-called dog-bone shape by a known flat shaping caliber (web thinning caliber), whereby H-shaped steel raw blanks 13 different in dimension of the flange portion are shaped.

Consequently, according to the shaping method according to this embodiment, the two kinds of H-shaped steel raw blanks 13 with different flange widths are shaped at the same roll chance from the slab materials having the same thickness and different widths, and the rolling mill train composed of two rolling mills such as the intermediate universal rolling mill 5 and the edger rolling mill 9 illustrated in FIG. 1 is used to apply reduction in a plurality of passes on the two kinds of H-shaped steel raw blanks 13, whereby intermediate materials 14 are shaped. The intermediate materials 14 are then subjected to finish rolling into product shapes in the finishing universal rolling mill 8, whereby H-shaped steel products 16 are produced. Here, rolling and shaping of greatly changing the flange half-width is not performed in an intermediate rolling step and a finish rolling step, so that two kinds of H-shaped steel products different in flange width are produced from the two kinds of H-shaped steel raw blanks 13 different in flange width.

Further, in the shaping method according to this embodiment, shaping is performed to bring the upper and lower end portions (slab end surfaces) of the material to be rolled A into contact with the caliber upper surface and the caliber bottom surface facing them in the final pass in the second caliber K2-1 to the fourth caliber K4-2. In short, the material to be rolled A is shaped while keeping dimensions with high accuracy in a shape following the caliber shape in each caliber rolling step. Accordingly, the raw blank corresponding to the first H-shaped steel product (small-width product) shaped using the third caliber K3-1 and the fourth caliber K4-1 and the raw blank corresponding to the second H-shaped steel product (large-width product) shaped using the third caliber K3-2 and the fourth caliber K4-2, are shaped into shapes following the respective caliber shapes. The above shaping enables efficiently and stably the raw blank corresponding to the first H-shaped steel product (small-width product) and the raw blank corresponding to the second H-shaped steel product (large-width product) while suppressing a shape defect such as right and left flange corresponding portions (the later-described flange portions 100) being nonuniform in material amount.

One example of the present invention has been explained above, but the present invention is not limited to the illustrated embodiment. It should be understood that various changes and modifications are readily apparent to those skilled in the art within the scope of the technical spirit as set forth in claims, and those should also be covered by the technical scope of the present invention.

The explanation that the first H-shaped steel product (small-width product) having a flange half-width of L1 and the second H-shaped steel product (large-width product) having a flange half-width of L2 (>L1) are shaped from the slab materials having the same thickness at the same roll chance, has been made in the above embodiment. As the H-shaped steel products having the two kinds of flange widths produced as above, the following dimensions are exemplified. Specifically, conceivable cases include the case of producing products having flange widths of 300 mm and 400 mm, and the case of producing product having flange widths of 400 mm and 500 mm, from the slab materials having the same thickness.

It is known that the dimension pitch of the flange width of a standard H-shaped steel product is 50 mm, and a case of separately shaping two kinds of H-shaped steel products different in flange width by 50 mm can be realized even by adjustment of a pass schedule or the like by the same caliber. However, in a case of separately shaping two kinds of H-shaped steel products different in flange width by more than 50 mm (for example, 100 mm), deformation of the material to be rolled has a problem in the intermediate rolling step or the like, requiring adjustment of the flange width from the stage of shaping the raw blank. Accordingly, in such a case, use of the method according to the above embodiment leads to production of two kinds of H-shaped steel products different in flange width by separate shaping at the same roll chance.

For example, it has been explained in the above embodiment that the first caliber K1 to the fourth caliber K4-2 may be engraved across both the sizing mill 3 and the rough rolling mill 4 or may be engraved on one of the rolling mills, but it is more desirable that the first caliber K1 to the third caliber K3-2 are engraved on the sizing mill 3 as a first rolling mill and the fourth calibers K4-1 and K4-2 are engraved on the rough rolling mill 4 as a second rolling mill as explained referring to Table 1.

Further, in a rolling facility having only one rolling mill that performs the rough rolling step, shaping may be performed in first heat using a roll on which the first caliber K1 to the third caliber K3-2 are engraved, then rolls are rearranged, and shaping may be performed in second heat using a roll on which the fourth calibers K4-1 and K4-2 are engraved.

Further, explanation has been made by exemplifying a slab as a material when producing H-shaped steel, but the present invention is naturally applicable also to other materials in a similar shape. In other words, the present invention is also applicable to a case of shaping, for example, a beam blank material to produce H-shaped steel.

INDUSTRIAL APPLICABILITY

The present invention is applicable to a producing technique of producing H-shaped steel using a slab or the like having, for example, a rectangular cross section as a material.

EXPLANATION OF CODES

-   -   1 rolling facility     -   2 heating furnace     -   3 sizing mill     -   4 rough rolling mill     -   5 intermediate universal rolling mill     -   8 finishing universal rolling mill     -   9 edger rolling mill     -   11 slab     -   12 flange corresponding portion     -   13 H-shaped steel raw blank     -   14 intermediate material     -   16 H-shaped steel product     -   20 upper caliber roll (first caliber K1)     -   21 lower caliber roll (first caliber K1)     -   25, 26 projection (first caliber K1)     -   28, 29 split (first caliber K1)     -   30 upper caliber roll (second caliber K2-1)     -   31 lower caliber roll (second caliber K2-1)     -   35, 36 projection (second caliber K2-1)     -   38, 39 split (second caliber K2-1)     -   40 upper caliber roll (second caliber K2-2)     -   41 lower caliber roll (second caliber K2-2)     -   45, 46 projection (second caliber K2-2)     -   48, 49 split (second caliber K2-2)     -   50 upper caliber roll (third caliber K3-1)     -   51 lower caliber roll (third caliber K3-1)     -   55, 56 projection (third caliber K3-1)     -   58, 59 split (third caliber K3-1)     -   60 upper caliber roll (third caliber K3-2)     -   61 lower caliber roll (third caliber K3-2)     -   65, 66 projection (third caliber K3-2)     -   68, 69 split (third caliber K3-2)     -   70 upper caliber roll (fourth caliber K4-1)     -   71 lower caliber roll (fourth caliber K4-1)     -   75, 76 projection (fourth caliber K4-1)     -   78, 79 split (fourth caliber K4-1)     -   80 upper caliber roll (fourth caliber K4-2)     -   81 lower caliber roll (fourth caliber K4-2)     -   85, 86 projection (fourth caliber K4-2)     -   88, 89 split (fourth caliber K4-2)     -   100 flange portion     -   A material to be rolled     -   T production line 

1. A method for producing H-shaped steel, the method comprising: a rough rolling step; an intermediate rolling step; and a finish rolling step, wherein: a rolling mill that performs the rough rolling step is engraved with a plurality of calibers configured to shape a material to be rolled, the number of the plurality of calibers being seven or more; shaping in one or a plurality of passes is performed on the material to be rolled in the plurality of calibers; the plurality of calibers comprise a plurality of wedging calibers as calibers at a previous stage provided with projections configured to create splits vertically with respect to a width direction of the material to be rolled, and a plurality of bending calibers as calibers at a subsequent stage configured to bend flange corresponding portions of the material to be rolled formed by the wedging calibers; the wedging calibers comprise calibers configured to create two kinds of splits different in length; the bending calibers comprise calibers having dimensions according to two kinds of flange corresponding portions different in length formed in the material to be rolled in the wedging calibers; and in the bending calibers, reduction is performed in a state where end surfaces of the material to be rolled are in contact with peripheral surfaces of the calibers in shaping in at least one pass or more.
 2. The method for producing the H-shaped steel according to claim 1, wherein each of the plurality of bending calibers is provided with projections configured to bend the flange corresponding portions by pressing the projections against the flange corresponding portions formed by the wedging calibers.
 3. The method for producing the H-shaped steel according to claim 1, wherein all of the projections provided in the plurality of wedging calibers have a tip angle of 25° or more and 40° or less.
 4. The method for producing the H-shaped steel according to claim 1, wherein: the plurality of bending calibers are provided at two stages in a configuration in which the calibers having dimensions according to the two kinds of flange corresponding portions different in length are provided with two kinds of projections different in tip angle, respectively; the projections of one of the bending calibers provided at the two stages have a tip angle of 70° or more and 110° or less; and the projections of another of the bending calibers have a tip angle of 130° or more and 170° or less.
 5. The method for producing the H-shaped steel according to claim 4, wherein: the rough rolling step is performed in a sizing mill and a rough rolling mill; the calibers at the previous stage of the plurality of wedging calibers and the plurality of bending calibers are engraved on a roll of the sizing mill; and the calibers at the subsequent stage of the plurality of bending calibers are engraved on a roll of the rough rolling mill.
 6. The method for producing the H-shaped steel according to claim 4, wherein the rough rolling step is performed by one rough rolling mill; shaping by the calibers at the previous stage of the plurality of wedging calibers and the plurality of bending calibers is performed in first heat by the rough rolling mill; and shaping by the calibers at the subsequent stage of the plurality of bending calibers is performed in second heat by the rough rolling mill.
 7. The method for producing the H-shaped steel according to claim 1, wherein materials same in thickness and different in width are used to produce H-shaped steels same in web height and different in flange width.
 8. A rolling apparatus performing a rough rolling step in production of H-shaped steel, wherein: the rolling apparatus is engraved with a plurality of calibers configured to perform shaping in one or a plurality of passes on a material to be rolled, the number of the plurality of calibers being seven or more; the plurality of calibers comprise a plurality of wedging calibers as calibers at a previous stage provided with projections configured to create splits vertically with respect to a width direction of the material to be rolled, and a plurality of bending calibers as calibers at a subsequent stage configured to bend flange corresponding portions of the material to be rolled formed by the wedging calibers; the wedging calibers comprise calibers configured to create two kinds of splits different in length; the bending calibers comprise calibers having dimensions according to two kinds of flange corresponding portions different in length formed in the material to be rolled in the wedging calibers; and the bending calibers have a configuration in which end surfaces of the material to be rolled are brought into contact with peripheral surfaces of the calibers in shaping in at least one pass or more.
 9. The rolling apparatus according to claim 8, wherein each of the plurality of bending calibers is provided with projections configured to bend the flange corresponding portions by pressing the projections against the flange corresponding portions formed by the wedging calibers.
 10. The rolling apparatus according to claim 8, wherein all of the projections provided in the plurality of wedging calibers have a tip angle of 25° or more and 40° or less.
 11. The rolling apparatus according to claim 8, wherein: the plurality of bending calibers are provided at two stages in a configuration in which the calibers having dimensions according to the two kinds of flange corresponding portions different in length are provided with two kinds of projections different in tip angle, respectively; the projections of one of the bending calibers provided at the two stages have a tip angle of 70° or more and 110° or less; and the projections of another of the bending calibers have a tip angle of 130° or more and 170° or less.
 12. The rolling apparatus according to claim 11, wherein: the rolling apparatus comprises a sizing mill and a rough rolling mill; the calibers at the previous stage of the plurality of wedging calibers and the plurality of bending calibers are engraved on a roll of the sizing mill; and the calibers at the subsequent stage of the plurality of bending calibers are engraved on a roll of the rough rolling mill. 